Sectionalizing and protective apparatus for single house transformer

ABSTRACT

Apparatus for controlling and protecting an electrical power distribution system from failure occurring in or between single dwelling transformers whose primary windings are energized from a sectionalizable loop. The apparatus includes three disconnect switches, one set of contacts in each being permanently connected in electrical series and the outermost ones of the series have their opposite contacts impermanently connected to different sections of the sectionalizable loop, while the intermediate one of the series has its opposite contacts removably connected to one end of a fuse, the opposite end of which connects with the primary of said transformer, whereby the transformer may be isolated without interrupting the continuity of the loop circuit, or a faulty section of the loop between different single dwelling transformers may be isolated and repaired or replaced without deenergizing any transformer energized from the loop.

[151 3,668,351 June 6, 1972 United States Patent Walbrun et al.

m s n mn E .mm M M mm im nm om mm DG Mm GS R N mmm @wm NTO www @wm WAT w[72] Inventors: Carl J. Walbrun; both of St. Louis C [73] Assignee;

[22] Filed:

Kearney-National Inc., St. Louis, Mo. July 30, 1969 [2l] Appl. No.:846,187

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FGE

FAINTEB-Jun 61912 SHEET 2 0F 5 FIGQB FIGA . supply circuit (commonlycalled a challenges other URD designs,

, 1 siscTioNALlziNG AND PROTECTIVE APPARATUS Fon SINGLE iioUsETRANsroRMER This invention relates generally to electric powerdistribuends of which are maintained at the same potential difference Y(distribution voltage) from ground, anda number of single dwellingtransformers have their primaries energized by tapping into s aidsingle-phase lateral somewhere between the ends of the lateral. Such adistribution circuit, if provided with appropriate switching devices ator near the individual transformers, can be sectionalized".so that whena fault occurs at a certain locus along the single-phase lateral, thatsection of the lateral may be isolated, deenergized and repaired,without interrupting the energization of all of the transformerssupplied by that lateral. While said patent discloses a number ofdifferent circuit arrangements for so sectionalizing such a loop") that:l) an individual transformer in the system'can be isolated withoutdeenergizing any other; or (2) the increments of the loop interveningtwo transformers can be deenergized without creating an outage at eitherof those two transformers; the control system disclosed by said patentfor accomplishment of (2) does not permit (l) to be accomplished withoutinterrupting the continuity of the loop. Y Accordingly, it is one objectof the present invention to provide for a sectionalizable distributionsystem of the kind which permits increments of the loop intervening twotransformers to be deenergized, and which permits individualtransformers to be isolated, with means whereby the latter can beaccomplished without interrupting the continuity ofthe loop.

On` the other hand, the more common sectionalizable system isrepresented by that shown and describedA in the article by-A.G. Dahl,entitled Transformer per house (URT) which appeared in the Sept. 5,1966, issue of Electrical World. In that system, each section ofunderground conductor between successive transformer stations isterminated in a separable male-female plug-in type connector, at leastvthe movable half of whichis `integrated with the distribution cable, andis manipulable to serve the dual purpose of a load break-and-make. Ateach transformer, there are two such male-female plug-in connectors, oneassociated with the underground section which extends to the right, andthe other associated withthe underground section whichextends to theleft ofthe given transformer station. Among the objections to thisarrangement are: that the movable half of such connectors beingrestrained by the inherent stiffness of the cable which must bend duringmanual circuitclosing, as well as during manualcircuit-making"operations cannot consistently, even by experts, bemanipulated with the instantaneity requisite to eliminate the hazard ofdrawing an exposed arc of dangerous proportions during the process ofopening or closing the circuit.

Accordingly, another object of the invention is to provide anarrangement of control and protective devices for the aforesaid purposewhich is substantially free of the haz-ards just mentioned, and is notonly safe to be manipulated by those skilled in the art, but much lesslikely tobe hazardous when manipulated by those unskilled in the artthan were the male-female plug-in connector type of devices.

These and other objectives are accomplished in accordance with thepresent invention by the provision, at each individual residence orbuilding, of an electric power service center, including an encasedcluster of modular control and protective devices, and a transformer.Different ones of the control devices are so connected at one pole tothe termini of dierent sections of asectionalizable loop; andpermanently connected at their other pole to each other with anintervening tap through another control device and a series connectedprotec- Y tematively,

preferable to provide the permanent electrical connection among the oneset of contacts in all three disconnect switches. Such electricalconnection is termed permanent for the reason that it can only be brokenby dismantling the cluster an operation which can be, and preferably is,such as to require some destruction or at least mutilation of someparts.

'The individual modules for the three disconnect switches can be, andpreferably are, identical, and include electrically conductive parts,all but one of which is confined within a capsule of insulatingmaterial, which capsule preferablycontains a cast-in set of complementalsemi-capsular casts of moldable insulating material confining anassembly of stationary contacts and arc-suppressing instrumentalities. v

The protective device, also included within the aforesaid cluster, is ofcomparable construction, but necessarily different in detail. lt, too,has all but one of its electrically conductive parts confined in aninsulating capsule. The protective instrumentality is preferably a fusereleasably mounted at one end upon an insulating handle, and adapted tobe inserted and withdrawn in bayonet-scabbard relationship relative tothe protective device capsule, so that the end of the fuse connectedwith the insulating handle makesconductive engagement with one set ofcontacts within the module, and the end of the fuse remote from thehandle makes electrical contact with another set of contacts within themodule, but spaced substantially a fuse length from the first set.

v While the insulating capsules of the disconnect switch modules differin detail from the insulating capsules of the protective device modules,the complemental semi-capsular casts within the disconnect switchcapsules are i enantiomorphously related so that a given semi-capsularcast constitutes half the internal chamber for containing theelectrically conductive parts which will be subject to arcing; and saidinternal chamber is itself preferably the core about which the externalinsulating capsule is molded. v

The invention contemplates that the semi-capsular casts forming saidinternal chamber be pre-molded with recesses, protub'erances, and otherinternal configurations which substantially conform to parts of, andhence position, the conductive parts of each module, as well as, whendesired,- non-conductive parts such as arc-snuffing devices and theiraccessories. i y

Once the conductive parts of a given device are assembled in onesemi-capsular cast with one set of contacts near one end, and anotherset of contacts near the other end of the cast, the companionsemi-capsular cast may be applied to complete the internal chamber, andthe exterior insulating capsule then cast or molded about the internalchamber and contents. Al-

the exterior capsules can be pre-cast in halves, the halves assembledabout the internal chamber (with contents) and permanently connected asby mutual solvent, or thermal sealing at the interfaces of the halves tocomplete the module. Then the complete modules are assembled into thefinal cluster with the electrically conductive parts at one end of eachdisconnect switch module all connected together in electrical series andheld together by sealing the insulating capsules of the three modulestogether. Alternatively, all of the respective internal chambers orotherv aforesaid series connected set. On two of the three disconnectswitch modules, the exposed electrically conductive part is intended tobe connected, by any suitable permanent or impermanent means, with theterminal of one section of the loop circuit. The third of the disconnectswitch modules has its exposed electrically conductive part connected toone set of contacts within the protective device module, while the otherset of contacts within the protective device module is exposed forpermanent or impermanent connection with the primary of the transformer`The protective device, or fuse module, is preferably connected to one ofthe disconnect switch modules (preferably the middle one) in such mannerthat the capsule of oneis sealed with the capsule of the other, therebymaking the lastmentioned electrical connection of permanent nature.

Preferably, the spaced contacts in all four modules are relativelystationary, that is to say,that they are fixed relative to theirrespective capsules, save only for resiliency of the parts intended toremovably receive a conductive member for selectively bridging thespaced contacts in any one module.

, An illustrative embodiment of the invention, as well as somealternatives for parts thereof, is shown in the accompanying drawings,in which: .Y

FIG. l is a circuit diagramdepicting the type of system to l which thepresent' invention applies, and diagrammatically illustratin'gthepositions in the circuits where the components of our electric powervservice center are located;

FIG. 2 is a perspective view, with one end cover substantially brokenaway to reveal the relationship of some parts therewithin, of theenclosure for a service center embodying the invention; v

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2, but showingthe cover (which was broken away in FIG. 2) in place;

FIG. 4 is a perspective view of the cluster of control and protectivemodules embodied in the center shown in FIGS. 2 and 3; i

v FIG. S is atop plan view of the cluster of modules shown in FIG. 4;

FIG. 6 is a view in side elevation taken along the plane designated 6 6in FIG. 5,'part being broken away to reveal the electrical connectionbetween the center module of FIG. andthe protective device moduletherebelow;

FIG. 7 is a longitudinal sectional View taken along line 7 7 of FIG. l2,and showing the relationship of electrically conductive and insulatingparts within aA disconnect switch module; v

FIG. 8 is a sectional view taken along line 8-8 of FIG. 12, and showingthe relationship of stationary conductive and insulating parts withinthe protective device module;

' FIG. 9 is a view in side elevation of a removable contact member foruse-in connection with the disconnect switch modules; l

FIG. l0 is a view in side elevation of a removable fuse and handle foruse in connection with the protective device module shown in FIG. 8;

FIG ll is a sectional view-corresponding to the sectional view in- FIG.8, but depicting an alternative construction for the protective devicemodule;

FIG. l2 is an operating end view of the cluster of control andprotective devices as seen through the open end of the enclosure shownin FIG. 2, with parts broken away to reveal the location ofinstrumentalities shown in dotted lines in FIG. 2;

FIG. 13 is a perspective view of the insulating handle portion ofthedeviceshownin FIG. as seen from the-fuse gripping end thereof;

FIG. 14 is a perspective view of the stationary contact set embodied inthe disconnect switch modules at the end thereof` where those contactsare permanently connected together among the three disconnect switchmodules;

FIG. 15 is a perspective view of the stationary contact set embodied inthe disconnect switch modules at the opposite end thereof from thelocation ofthe set shown in FIG. 14;

4 FIG. 16 is a perspective view of one o f the arc-extinguishingclappers shown in FIG. 7; 1 l

FIG. 17 is a perspective view of an arc-extinguishing halfliner for theinsulating capsule shown in FIG. 7; and

FIG. 18 is a perspective view of the fuse keeper shown in FIGS. 2andvl2.

In the distribution system shown in FIG. 1, the generator 1 producesthree-phase voltage which energizes the primaries 2 of a three-phasetransformer, whose secondary 3 is at a higher voltage for transmission.v

At a chosen locality, the transmission voltage energizes the primary 4of a three-phase transformer or bank of transformers, whose secondary 5is a Y-connected, grounded neutral, producing the distribution voltageof, say, 7,200 volts between ground and each of conductors 6, 7 and 8,respectively. The several distribution conductors 6, 7 and 8, which maybe either overhead lines or underground lines, extend to differentlocalities in the proximity of each other, line 8 serving asectionalizable loop 9, line 7 sectionalizable a sectionalizable loop10, and line 6 serving a sectionalizalbe underground loop ll'shown onlarger scale than the loops9 and 10 in order to illustrate the detail ofthe circuit control devices embodied therein in accordance with thepresent invention. It will be observed that the loop 1 1- connects withdistribution conductor 6 at two points 12 and 13. Hence, both ends oftheA loop l lare at y substantially the same potential difference fromground. As "shown, the underground loop 1l is sectionalizable into fivesections located, respectively, between fused switch 14 and switch l5,between switch 16 and switch 17, between switch 18 and switch 19,between switch 20 and switch 21. Normally the loop operates with aswitch near the mid-point in the loop (e.g., 18) in open circuitposition, but energization of all instrumentalities connected with theloop is continued by supplying those on one side of the open switch fromconnection l2, and those on the other side of the open switch from point13. Hence, if a ditch-digger mutilates the underground cable betweenswitches 16 and 17, for example, those switches may .be opened toisolate the mutilated section of cable, and normally-open switch 18closed, without requiring outage of any one of transformers 22, 23, 24or 25,.while the'mutilated cable is being repaired. In the arrangementsdiagrammatically illustrated in FIG. 1, transformers 22, 23, and 24 areeach a part of a service center constructed in accordance with thepresent invention,` but transformer 25 is different, as willy be laterdescribed. v

The secondary of each of the transformers, however, is shown as beingdesigned to supply either or both of l20 volt or 240 volt service to theadjacent dwelling.

The service center, constructed in accordance with lthe presentinvention as'seen in FIGS. 2 and 3, includes an enclosurer26 of sheetmetal, or other appropriate weather-resisting material, having tworemovable ends 27 and 28, the latter of which is shown almost whollybroken away in FIG. 2. Within switch 34 contained within module 35 ofthecluster shown in FIG. 4. To assure that the fuse 33 is not manuallydisconnected without first having opened disconnect switch 34, a latch36 is mounted on a'panel 37 of the service center in such manner that itoverhangs the end of fuse cap 330, thus preventing removal thereoffrom-the module 32 unless and until switch cap 340 is first removed. Toaccomplish the latter, latch 36 is pivotally mounted upon a bolt 38extending through the insulating panel 37, and is contoured as shown inFIG. 18, so that the lower apron portion 39 overhangs the upper half ofthe end of fuse cap 330, while the upper portion 5 40 of latchl 36 fitsbeneath switch cap 340, and is thereby prevented from being rotated inthe clock-wise direction', as seen in FIG. 2, unless and until theswitch cap 340 is moved out of the way.

The internal construction of module 32 is illustrated in FIG. 8, whichis a section taken along line 8-8 of FIG. 12, i.e., diamet'ricalsectionof the capsule 41 and its contained conductive parts (except thatportions of the conductive parts are shown in elevation). The capsule41, of moldable insulating material, was preferably molded with spacedelectrically conductive fuse-engaging parts 42 and 43 in situ. Such acapsule as 41, when cast about the electrically conductive parts asshown, produces the fuse module 32 seen in FIGS. 2, 3, 4 and 6. Theconductive part 42 consists of a ring 44, having a cylindrical stud 45projecting radially outward therefrom. Through the wall of capsule 4l,there extends a cylindrical sleeve 46 which embraces a stud 45 and asplit metallic tube 47 of pro# portions such that the split 48 must beforced open slightly to engage over stud 45, so that when the openingforce is relaxed, the' resilience of the lcounterpart thereof in module35 later to be described.

f At the closed end of capsule 41, there is a cup-shaped base 43 havinga lug 31 extending outwardly through the wall of the capsule 4l. Thecapsule is also preferably molded about such base and lug. A bifurcatedresilient clip 49 is also mounted in the cup-shaped part 43,`so as toresiliently grip the conductive thimble 50 of a fuse cartridge 51, suchas that shown in FIG. 10. The opposite end of the fuse cartridge has athimble 52 provided with a circumferential bead 53, and the fuse cap 330has a pair of jaws 54 (see FIG. 13) which terminate in a discontinuouschannel 55 of curvature such as to be congruent with that of the bead 53on the fuse cartridge. The jaws 54 are mounted upon an interior portionof the insulating fuse cap 330 by means of a bolt 56 and nut 57, whichmay be relaxed to permit the insertion and removal of a fuse cartridge,such as 51, from between the opposite jaws 54; and when a new fuse isinserted, the bolt-nut combination 56-57 may be tightened down over thebead ofthe new fuse cartridge. Each of the jaws 54 is equipped with apair of resilient tangs 58 for electrically conductive engagement withthe inner'periphery of ring 44 when a fuse cartridge and the fuse capare in the position shown in FIG. 6. v

The module 35 previously referred to is the center one of threesubstantially identical modules shown in FIG. 5, and the outer ones aredesignated 59 and 60, respectively. Each of these thre'e modules isconstructed of identical'parts, save in one particular to be notedhereinafter. Each includes an insulating capsule 61formed of moldabledielectric material. One such capsule is shown in FIG. 7, .and consistsof a wall of dielectric material substantially circular in cross-sectionwhich was molded about an assembled pair of half-liners 62 and contentsof the character shown in FIGS. 7, 14, and 16. The use of an interiorsub-assembly of half-liners 62 and contained components, is a matter ofeconomy because it enables less of the complete capsule to be made ofmore expensive arc-resisting material than would be desirable withoutthe liner assembly.

In the embodiment shown in FIGS. 7 and 17, the half-liners 62 are castparts of insulating material which resistant, but may, if desired, havesome arc-suppressing qualities, depending upon the material of whichthey are made. Adjacent the closed end of half-liner 62, .there is astationary contact assembly consisting of a ring 63 (see FIG. 14) ofconductive material having riveted thereto four resilient conductivefingers 64 and a metallic bridge 65 having a central aperture 66.Integral with the ring 63, there are two studs 67 and 68 of cylindricalcross-section, the latter of which, as seen in FIG. 7, is substantiallyshorter than the former, which is the condition in which the element isemployed in modules 59 and 60. In module 35, on the other hand, theconstruction is as shown in FIG. `14, where the studs 67 and 68' are ofthe same length radially of ring 63. i

split tube 47 grips stud 45, as well as the is not only arc- Theconstruction of the stationary contact assembly at the closed end ofmodule 35 differs from that at the closed ends of modules 59 and 60, andis dictated by the fact that the invention contemplated connecting thecontact assemblies at the closed ends of all three modules 59, 35, and60 in permanent electrical series. This requires that the center module35 have its studs 67 and 68' extend as far in both directions as thestud 67 extends in one direction for modules 59 and 60. This dfferencein the length of stud 68 versus stud 68 does not, however, necessitateany change in the mold in which the three capsules 6l are made. All suchcapsules are preferably made with accommodation at both sides for only ashort stud, such as 68, so that the section of wall delineated by dottedlines in FIG. 7 and designated 694may be drilled out or left intact, asdesired, depending upon the ultimate disposition of the particularcapsule in the complete cluster.

As described in connection with shown in the broken-away portions ofFIG. 5, stud 67 of module 59 is electrically connected with stud 68' ofmodule 35 by means of a split resilient tube 70 of conductive materialwhich may be confined within a sleeve 71. And an identical connection ismade between modules 35 and 60.

The stationary contact assembly located toward the open end of modules59, 35 and 60 is illustrated in FIG. 15, and is similar with that shownin FIG. 14, but differs in that it has no bridge like 65, and in that,in all instances, the relative lengths of the radially projecting studs72 and 73 are as shown in FIG. l5 (which is comparable to that shown inFIG. 7 for the contact assembly at the closed-end of an outside module).However, the stud 73 is axially bored and threaded as indicated at 74 toreceive a bolt to which lugs 75 and 76 for modules 59.

and 60 respectively may be connected, as shown in FIG. 12, while onmodule 35, the boring and threading 74 is not necessary, but it does noharm in effectuating the connection sh'own in FIG. 6 between module 35and module 32, which again is of the same split sleeve type as thatpreviously described.

To complete a circuit between the spaced stationary contact members inany one of the three modules 35, 59, and 60, each is provided with aremovable stab such as that shown in FIG. 9. Such a stab consists of aninsulating cap 34 having a pilot portion 77 in which is anchored one endof a rod 78 of copper, or other conductive material, having a taperednose 79 which may, if desired, be tipped with arc-resisting materialsuch as copper-tungsten alloy. The length of the rod 78 is at leastsufficient that the tip 79 has passed through and beyond the locus ofengagement with fingers 64 before the insulating cap 34 has come to restagainst the open end of the module. When the last-mentioned position isreached, the fingers 80 of the Contact assembly, shown in FIG. 15, willbe in conductive engagement with rod 78, thereby completing a circuitbetween stud 73 and its associated components, and stud 67 and itscounterpart in all three modules 59, 35 and 60.

The correlation of the several contacts in the diagrammatic showing ofFIG. l with the physical showing of FIGS. 2-8, l2, 14 and l5 will beclear to persons skilled in the art from the following table:

Module Contact Diagrammatic Side 59 80 equates with 17 Right 59 64equates with 17 Left 60 80 equates with 18 Right 60 64 equates with 18Le 35 64 equates with 34 Right 35 80 equates with 34 Left 36 44 equateswith 33 Right 36 43 equates with 33 Left FromA FIG. 17, it will beapparent that the identical halfliners 62, two of which constitute acomplete liner assembly for use on the interior of the capsule of eachdisconnect switch module, are constructed not only to accommodate therelathe fuse module 32, and as tively stationary contact assembliesshown in FIGS. 14 and 15, but also to delineate a constricted passagewaybetween said stationary contact assemblies. Furthermore, each suchhalfliner is compartmentalized lengthwise by spaced partitions 81, sothat the space occupied by the relatively stationary contacts 64 issubstantially isolated from the space occupied by the relativelystationary contacts 80; and between the two, there is accommodation fora plurality of sets of arc-quencher elements 82, one of which isillustrated in FIG. 16. These arcquencher elements are, in the formillustrated, substantial segments of a cylinder of melamine resin, orother moldable material` having arc-quenching properties. In FIG. 16,the planar side of the segment is addressed toward the reader, and itwill be observed that a half-conical recess 83 is formed at one side ofthe planar surface. ln one or more of the compartments delineated bypartitions 81, a pair of the arc-quenching wipers or clappers 82is'mounted with its individual segments arranged so that the recess 83of one complements the recess 83 of its companion when the rod 78 of theswitching stab is removed. Thus, the disposition of the recesses 83 inpaired clapper elements is in position to funnel in the tip 79 of rod 78when next inserted, and to guide the rod between the paired clapperelements 82.

On the arcuate side of each clapper segment 82, there is a recess 84,shown in dotted lines in FIG. 16, for accommodating a spring 85, whichis seated on a boss 86 projecting upwardly from one half of the liner,and downwardly from the other half, as clearly shown in FIG. 7. Suchspring mounting of the clapper segments 82 resiliently urges them towardeach other,`so that when, during the withdrawal of rod 78, the tip 79departs from between a given pair of clappers 82, they clap together,inserting thearc-guiding material directly into the path of theestablished arc, and thereby causing the emission of arc-suppressinggases. As clearly shown in FIG. 17, each of the partitions 81 has acentral arcuate cutout 87 which together not only define a passagewayfor the rod 78, but constrict that passageway at tive separatedlocations.

The two halves 62 of the composite liner are identical, and areassembled together in reverse orientation, so that circumferentially onetruly complements the other, and they interlock along their parting linewith a tongue and groove connection, the tongue 88 extending along theright half (as seen in FIG. 17) of the perimeter, and the groove 89extending along the left half.

As shown in FIGS. 2 and l2, the studs 73 of the stationary contactassemblies near the open ends of modules 59 and 60 are respectivelyequipped with terminal lugs 75 and 76 for removably receiving the end ofcable90 and the end of cable 91, respectively. The cable end V90 is oneterminal of a section of the underground loop 1l, as, for example, thesection thereot` which extends between switches 16 and 17 in FIG. 1. Thecable end 91 is one terminal of an adjacent section of the undergroundloop 11, as, for example, the section thereof which extends betweenswitches 18 and 19 in FIG. 1.

As shown in FIG. 12, the lugs 75 and 76 may each be equipped with astirrup 92 which provides a convenient place for applying a groundingclamp, while the service controlv center is being connected,disconnected, or worked on. The cables 90 and 91, as well as theterminals 75 and 76 and the associated stirrups 92, are, of course,disposed behind the insulating panel 37, as seen in FIG. 2.

Flg. 11 illustrates an alternative form of fuse module which differsfrom that shown in FIG. 8 in the respect that the clip 149, which is thecounterpart of clip 49 in FIG. 8, has a terminal post 150 which extendsout through the end of the dielectric capsule, rather than out throughthe bottom as shown for 3l in FIG. 8.

As clearly shown in FIGS. 2 and 3, the service center also includes ameter 93 connected in the circuit 94 of the transformer secondary, andthe meter is disposed so that its dial can be read through a window 95without removing end panel 27.

From the foregoing description, those skilled in the art shouldunderstand the invention and realize that the service center is intendedto be mounted at or near ground level, so that it is convenientlyaccessible whenever there is need for authorized persons to manipulateone of the disconnect switches, or to inspect or replace the fuse. Suchlocation of such an apparatus has,v by some alarmists, been consideredto pose a hazard to children whose curiosity may lead them to remove acover. Accordingly, the removable ends 27 and 28 are each equipped witha latch 96, manipulable only by turning a keeper 97, and the keeper isarranged to be padlocked, in the position shown in FIG. 3, by having thebow of the padlock extend through the hole 98 in the keeper, as well asa hole in lug 99 thereadjacent.

The modular arrangement of control and protective devices hereindisclosed is substantially safe because with the permanent electricalconnection of the substantially stationary contacts at the closed end ofeach disconnect switch module, the arc drawn when the stabs of eithermodule 59 or module 60 are withdrawn is minimal, and when the stab ofmodule 35 is withdrawn, `the only circuit interrupted is that whichleads directly to the transformer component of the particular servicecenter and none other'. As previously pointed out, the fuse modulecannot, because of the interlocking relationship of latch 36, be movedout of operating position without first open-circuiting the disconnectswitch in module 35` In sum, no hazardous arc can be drawn from theapparatus disclosed if the stabs of the respective disconnect switchmodules are withdrawn rapidly and inserted rapidly. To completelyeliminate the hazard involved when unskilled persons manipulate theparts of the apparatus exposed on the insulating panel 37 when cover 28is removed, the length of the modules 35, 59, and 60, as well as thelength of the insulation-handle on the stab shown in FIG. 9, may beincreased so that the modules are nearly twice aslong as their liners62, and the insulation on the stab extends from the inside of cap 34 fora distance at least equal to the distance the tip 79 of rod 78 musttravel from the position shown in FIG. 7 to a position where rod 78 haslost contact with fingers 80 and their associated electrically-liveparts. With such increase in length of the several modules, it becomesimpossible for a person to touch any part of rod 78 while that rod is inconductive relationship with a stationary contact of the module.

In the foregoing description, the capsules suchas 41 and 61, which formthe insulatingenclosures (save at one end) of the several modules 32,35, 59 and 60, have been described as each being individually molded inone piece, but it should be understood that Yif and when desired: thedielectric capsules can be of pluri-piece construction, assembled aboutthe conductive and arc-snufting parts, and securely unified together asby solvent or thermal sealing, or otherwise; or given the requisitemolding equipment, the entire cluster of capsules can be molded in oneintegral piece. Moreover, since for service centers like that includingtransformer 21 the cluster of capsules may be reduced to two (one like32, the other like 35 it is feasible to mold those two capsules in onepiece for optional addition of capsules like 59 and 60 when the clusteris to be used in service centers like that including single dwellingtransformer 22, 23, or 24.

While one complete embodiment of the invention has been disclosed indetail, and various modifications described, it is not to be understoodthat the invention is limited to the details of the foregoingdisclosure.

We claim:

l. Sectionalizing and protective apparatus for single dwellingtransformers comprising a cluster of:

a. three capsules of moldable insulating material;

b. another capsule of moldable insulating material; all said capsuleshaving one end open and one end closed, said said partitions beingcentrally relieved to provide a passageway extending axially from saidopen end toward but terminating short of the closed end of saidcapsules, and said capsules (b) having a central passageway of greaterradial dimension than that in said partitions; said capsules each havingcast therein:

e. a pair of resilient contacts near opposite ends of and adjacent therespective passageways;

said capsules (a) having:

f. conductive means extending from the resilient contacts at one end ofthe respective capsules to connect the corresponding resilient contactsin allcapsules (a) together; and

at least two of said capsules (a) having:

g. conductive means extending from the resilient contact at the otherend of said passageway to the exterior of said capsules for connectionwith a source of power.

2. The apparatus of claim 1 wherein the capsule (b) accommodates a fuse,and the resilient contact at one end thereof is conductively connectedto the conductive means (g) of one of said capsules (a).

3. The apparatus of claim l wherein each capsule (a) is provided withremovable stab means for interconnecting the resilient contacts (e)thereof, and said stab means includes a manipulating part of insulatingmaterial which is disposed on the exterior of a capsule when theresilient contacts (e) thereof are interconnected by said stab means.

4. A circuit interruptor comprising a capsular cast of moldableinsulating material and having a hollow interior and at least one openend, a first relatively stationary resilient contact mounted in saidhollow interior remote from said open end, a second relativelystationary resilient contact mounted in said hollow interior in spacedrelationship with the first but nearer said open end, compartment meansdefining a constricted passageway between said first and said secondrelatively stationary contacts, arc-snufting means adjacent saidconstricted passageway, a removable stab having:

a. a conductive part of length sufficient to bridge the gap between saidrelatively stationary contacts, and

b. an insulating part extending outwardly beyond said conductive partfor a distance sufficient that when the conductive part engages theFirst-mentioned resilient contact, said insulating part occupies saidopen end and extends outwardly of said capsular cast, and

fixed conductive means extending from said relatively stationarycontacts respectively through said capsular cast to provide connectingterminals.

5. The circuit interruptor of claim 4 wherein said relatively stationaryresilient contact remote from said open end is an assembly of:

c. a support member having an outside peripheral contour substantiallymatching the inside peripheral contour of said hollow interior, Y

. oppositely disposed resilient finger members mounted incircumferentially spaced relationship on said support member,

. a bridging member of conductive material mounted on said supportmember in electrically conductive relationship with said finger membersand having a central hole to accommodate passing of said conductive part(a) therethrough` and conductive means projecting radially' outward fromsaid support member through the wall of said capsular cast.

1. Sectionalizing and protective apparatus for single dwellingtransformers comprising a cluster of: a. three capsules of moldableinsulating material; b. another capsule of moldable insulating material;all said capsules having one end open and one end closed, said capsules(a) being internally subdivided by radially extending partitions toprovide: c. compartments at opposite ends thereof for accommodatingpaired relatively stationary and resilient electrical contacts, and d.at least one intervening compartment for accommodating arcextinguishingmeans, said partitions being centrally relieved to provide a passagewayextending axially from said open end toward but terminating short of theclosed end of said capsules, and said capsules (b) having a centralpassageway of greater radial dimension than that in said partitions;said capsules each having cast therein: e. a pair of resilient contactsnear opposite ends of and adjacent the respective passageways; saidcapsules (a) having: f. conductive means extending from the resilientcontacts at one end of the respective capsules to connect thecorresponding resilient contacts in all capsules (a) togeTher; and atleast two of said capsules (a) having: g. conductive means extendingfrom the resilient contact at the other end of said passageway to theexterior of said capsules for connection with a source of power.
 2. Theapparatus of claim 1 wherein the capsule (b) accommodates a fuse, andthe resilient contact at one end thereof is conductively connected tothe conductive means (g) of one of said capsules (a).
 3. The apparatusof claim 1 wherein each capsule (a) is provided with removable stabmeans for interconnecting the resilient contacts (e) thereof, and saidstab means includes a manipulating part of insulating material which isdisposed on the exterior of a capsule when the resilient contacts (e)thereof are interconnected by said stab means.
 4. A circuit interruptorcomprising a capsular cast of moldable insulating material and having ahollow interior and at least one open end, a first relatively stationaryresilient contact mounted in said hollow interior remote from said openend, a second relatively stationary resilient contact mounted in saidhollow interior in spaced relationship with the first but nearer saidopen end, compartment means defining a constricted passageway betweensaid first and said second relatively stationary contacts, arc-snuffingmeans adjacent said constricted passageway, a removable stab having: a.a conductive part of length sufficient to bridge the gap between saidrelatively stationary contacts, and b. an insulating part extendingoutwardly beyond said conductive part for a distance sufficient thatwhen the conductive part engages the first-mentioned resilient contact,said insulating part occupies said open end and extends outwardly ofsaid capsular cast, and fixed conductive means extending from saidrelatively stationary contacts respectively through said capsular castto provide connecting terminals.
 5. The circuit interruptor of claim 4wherein said relatively stationary resilient contact remote from saidopen end is an assembly of: c. a support member having an outsideperipheral contour substantially matching the inside peripheral contourof said hollow interior, d. oppositely disposed resilient finger membersmounted in circumferentially spaced relationship on said support member,e. a bridging member of conductive material mounted on said supportmember in electrically conductive relationship with said finger membersand having a central hole to accommodate passing of said conductive part(a) therethrough, and f. conductive means projecting radially outwardfrom said support member through the wall of said capsular cast.